Cerebral edema is associated with traumatic brain injury. The overall HYPOTHESIS of the proposed intervention is that free water removed from the brain following traumatic injury will minimize cerebral edema. Approach: The applicant proposes to complete preclinical development of an innovative catheter for the reduction of cerebral edema. The initial clinical application of this catheter will be traumatic brain injury, and will involve replacing standard ventricular drains with Water Removal Therapy (WRT) catheters that 1) remove fee water from the CS, 2) remove bulk cerebral spinal fluid (CSF) samples, and 3) monitor intracranial pressure. Removal of water free will increase osmolarity of the CSF, which will theoretically result in removal of interstitial brain water and improved nutrient exchange, creating improved cerebral perfusion. Phase I studies have demonstrated that human CSF osmolarity increases with traumatic brain injury and WRT catheters can remove water from CSF at clinically significant rates that improves water movement in ex vivo ovine cerebral tissue. Specific Aims: (1) Build and test WRT catheters in vitro to meet human study requirements. (2) Test WRT catheters in vivo in a non-injury swine model. These tests will establish device safety under different operating parameters. (3) Measure cerebral changes (pressure and swelling) and functional outcome with ventricular WRT catheter treatment in vivo after cold freeze injury in swine model. Acute (6 hours) and chronic (1 week) randomized controlled injury studies will be undertaken. Significance: Cerebral edema after traumatic injury and severe stroke is a life threatening condition that is refractory to conventional treatments in a significant population of patients. Current treatments (i.e. hyperventilation, osmotic agents, or hypothermia) are associated with serious side effects that increase with prolonged use. Successful completion of Phase II aims will make human studies of WRT catheters possible. [unreadable] [unreadable]